HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ballaux, J. C. Articles by Peaslee, D. E. Search for Related Content PubMed Articles by Ballaux, J. C. Articles by Peaslee, D. E. Agricola Articles by Ballaux, J. C. Articles by Peaslee, D. E.

Relationships between Sorption and Desorption of Phosphorus by Soils

ABSTRACT

A routine soil test can indicate the level of extractable P in the soil and the fertilizer P requirement if the test is calibrated for that soil type. Without calibration data, the test will indicate only the level of extractable P. The limited amount of calibration data could be extended more accurately over ranges of soils if soils could be categorized according to their capacities for sorption-desorption of P.

Relationships between the sorption and desorption of P were investigated for five soils ranging in clay content from 16 to 51%. Langmuir adsorption isotherms for some soils were curvilinear when the P concentration in the equilibrium solution was >10 µg/ml. To evaluate sorption at higher concentrations of P, values of adsorption maxima (b) and indices of bonding energy (k) were estimated from tangents to six segments of each isotherm. Within each soil, the six pairs of b and k values were related according to the equation k = (a/b)ⁿ, where n was a unique characteristic for each soil.

Desorption was measured by adding P to soils, incubating, then extracting with anion exchange resin. The relative increases in extractable P among the five soils was highly correlated (r = 0.99**) with values of n for the soils. Decreasing n values among soils indicated greater sorption capacities and lower tendencies to release P. Neither b nor k were consistently correlated with the relative increases in extractable P. The data suggest that n may provide an index of the sorption-desorption properties of soils for grouping them on the basis of their reaction with added P and its subsequent release.

Received for publication June 12, 1974. Accepted for publication January 2, 1975.